On 04/11/2014 11:56 AM, Sekhar Nori wrote: > On Friday 11 April 2014 02:20 PM, Peter Ujfalusi wrote: >> On 04/11/2014 11:17 AM, Sekhar Nori wrote: >>> On Tuesday 01 April 2014 06:36 PM, Peter Ujfalusi wrote: >>>> Use the EVENTQ_1 for default and leave the EVENTQ_0 to be used by high >>>> priority channels, like audio. >>>> >>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> >>> >>> Acked-by: Sekhar Nori <nsekhar@xxxxxx> >>> >>>> --- >>>> arch/arm/common/edma.c | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c >>>> index 86a8b263278f..19520e2519d9 100644 >>>> --- a/arch/arm/common/edma.c >>>> +++ b/arch/arm/common/edma.c >>>> @@ -1546,7 +1546,8 @@ static int edma_of_parse_dt(struct device *dev, >>>> >>>> pdata->queue_priority_mapping = queue_priority_map; >>>> >>>> - pdata->default_queue = 0; >>>> + /* select queue 1 as default */ >>> >>> It will be nice to expand the comment with explanation of why this is >>> being chosen as default (lower priority queue by default for typical >>> bulk data transfer). >> >> Yes, extended comment is a good idea. >> >> For the next version I think I'm going to change the code around default >> TC/Queue and the non default queue selection, mostly based on Joel's comment: >> >> EVENTQ_1 as default queue. >> Set the EVENTQ_1 priority to 7 >> EVENTQ_0 priority is going to stay 0 and EVENTQ_2 as 2 >> >> Add new member to struct edma, like high_pri_queue. >> When we set the queue priorities in edma_probe() we look for the highest >> priority queue and save the number in high_pri_queue. >> >> I will rename the edma_request_non_default_queue() to >> edma_request_high_pri_queue() and it will assign the channel to the high >> priority queue. >> >> I think this way it is going to be more explicit and IMHO a bit more safer in >> a sense the we are going to get high priority when we ask for it. > > Sounds much better. I had posted some ideas about adding support for > channel priority in the core code but we can leave that for Vinod and > Dan to say if they really see a need for that. If we do it via the dmaengine core I think it would be better to have a new flag to be passed to dmaengine_prep_dma_*(). We could have for example: DMA_PREP_HIGH_PRI as flag to indicate that we need high priority DMA if it is possible. We can watch for this flag in the edma driver and act accordingly. ALSA's dmaengine_pcm_prepare_and_submit() could set this flag unconditionally since audio should be treated in this way if the DMA IP can do this. Not sure what to do with eDMA's 8 priority level. With that we could have high priority; low priority; low, but not the lowest priority; about in the middle priority; etc. We could have also new callback in the dma_device struct with needed wrappers to set priority level, but where to draw the range? High, Mid and Low? Range of 0 - 10? -- Péter -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
